NFSv4: Fix delegation return in cases where we have to retry

[ Upstream commit be20037725d17935ec669044bd2b15bc40c3b5ab ]

If we're unable to immediately recover all locks because the server is
unable to immediately service our reclaim calls, then we want to retry
after we've finished servicing all the other asynchronous delegation
returns on our queue.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/nfs/delegation.h

@@ -36,6 +36,7 @@ enum {
 	NFS_DELEGATION_REVOKED,
 	NFS_DELEGATION_TEST_EXPIRED,
 	NFS_DELEGATION_INODE_FREEING,
+	NFS_DELEGATION_RETURN_DELAYED,
 };
 
 int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred,